1 /* GStreamer X-based Overlay

     2  * Copyright (C) 2003 Ronald Bultje <rbultje@ronald.bitfreak.net>

     3  *

     4  * x-overlay.c: X-based overlay interface design

     5  *

     6  * This library is free software; you can redistribute it and/or

     7  * modify it under the terms of the GNU Library General Public

     8  * License as published by the Free Software Foundation; either

     9  * version 2 of the License, or (at your option) any later version.

    10  *

    11  * This library is distributed in the hope that it will be useful,

    12  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    14  * Library General Public License for more details.

    15  *

    16  * You should have received a copy of the GNU Library General Public

    17  * License along with this library; if not, write to the

    18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

    19  * Boston, MA 02111-1307, USA.

    20  */

    21 

    22 /**

    23  * SECTION:gstxoverlay

    24  * @short_description: Interface for setting/getting a Window on elements

    25  * supporting it

    26  *

    27  * <refsect2>

    28  * <para>

    29  * The XOverlay interface is used for 2 main purposes :

    30  * <itemizedlist>

    31  * <listitem>

    32  * <para>

    33  * To get a grab on the Window where the video sink element is going to render.

    34  * This is achieved by either being informed about the Window identifier that

    35  * the video sink element generated, or by forcing the video sink element to use

    36  * a specific Window identifier for rendering.

    37  * </para>

    38  * </listitem>

    39  * <listitem>

    40  * <para>

    41  * To force a redrawing of the latest video frame the video sink element

    42  * displayed on the Window. Indeed if the #GstPipeline is in #GST_STATE_PAUSED

    43  * state, moving the Window around will damage its content. Application

    44  * developers will want to handle the Expose events themselves and force the

    45  * video sink element to refresh the Window's content.

    46  * </para>

    47  * </listitem>

    48  * </itemizedlist>

    49  * </para>

    50  * <para>

    51  * Using the Window created by the video sink is probably the simplest scenario,

    52  * in some cases, though, it might not be flexible enough for application

    53  * developers if they need to catch events such as mouse moves and button

    54  * clicks.

    55  * </para>

    56  * <para>

    57  * Setting a specific Window identifier on the video sink element is the most

    58  * flexible solution but it has some issues. Indeed the application needs to set

    59  * its Window identifier at the right time to avoid internal Window creation

    60  * from the video sink element. To solve this issue a #GstMessage is posted on

    61  * the bus to inform the application that it should set the Window identifier

    62  * immediately. Here is an example on how to do that correctly:

    63  * <programlisting>

    64  * static GstBusSyncReply

    65  * create_window (GstBus * bus, GstMessage * message, GstPipeline * pipeline)

    66  * {

    67  *  // ignore anything but 'prepare-xwindow-id' element messages

    68  *  if (GST_MESSAGE_TYPE (message) != GST_MESSAGE_ELEMENT)

    69  *    return GST_BUS_PASS;

    70  *  

    71  *  if (!gst_structure_has_name (message->structure, "prepare-xwindow-id"))

    72  *    return GST_BUS_PASS;

    73  *  

    74  *  win = XCreateSimpleWindow (disp, root, 0, 0, 320, 240, 0, 0, 0);

    75  *  

    76  *  XSetWindowBackgroundPixmap (disp, win, None);

    77  *  

    78  *  XMapRaised (disp, win);

    79  *  

    80  *  XSync (disp, FALSE);

    81  *   

    82  *  gst_x_overlay_set_xwindow_id (GST_X_OVERLAY (GST_MESSAGE_SRC (message)),

    83  *      win);

    84  *   

    85  *  gst_message_unref (message);

    86  *   

    87  *  return GST_BUS_DROP;

    88  * }

    89  * ...

    90  * int

    91  * main (int argc, char **argv)

    92  * {

    93  * ...

    94  *  bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));

    95  *  gst_bus_set_sync_handler (bus, (GstBusSyncHandler) create_window, pipeline);

    96  * ...

    97  * }

    98  * </programlisting>

    99  * </para>

   100  * </refsect2>

   101  */

   102 

   103 #ifdef HAVE_CONFIG_H

   104 #include "config.h"

   105 #endif

   106 

   107 #include "xoverlay.h"

   108 

   109 static void gst_x_overlay_base_init (gpointer g_class);

   110 #ifdef __SYMBIAN32__

   111 EXPORT_C

   112 #endif

   113 

   114 

   115 GType

   116 gst_x_overlay_get_type (void)

   117 {

   118   static GType gst_x_overlay_type = 0;

   119 

   120   if (!gst_x_overlay_type) {

   121     static const GTypeInfo gst_x_overlay_info = {

   122       sizeof (GstXOverlayClass),

   123       gst_x_overlay_base_init,

   124       NULL,

   125       NULL,

   126       NULL,

   127       NULL,

   128       0,

   129       0,

   130       NULL,

   131     };

   132 

   133     gst_x_overlay_type = g_type_register_static (G_TYPE_INTERFACE,

   134         "GstXOverlay", &gst_x_overlay_info, 0);

   135     g_type_interface_add_prerequisite (gst_x_overlay_type,

   136         GST_TYPE_IMPLEMENTS_INTERFACE);

   137   }

   138 

   139   return gst_x_overlay_type;

   140 }

   141 

   142 static void

   143 gst_x_overlay_base_init (gpointer g_class)

   144 {

   145   GstXOverlayClass *overlay_class = (GstXOverlayClass *) g_class;

   146 

   147   overlay_class->set_xwindow_id = NULL;

   148 }

   149 

   150 /**

   151  * gst_x_overlay_set_xwindow_id:

   152  * @overlay: a #GstXOverlay to set the XWindow on.

   153  * @xwindow_id: a #XID referencing the XWindow.

   154  *

   155  * This will call the video overlay's set_xwindow_id method. You should

   156  * use this method to tell to a XOverlay to display video output to a

   157  * specific XWindow. Passing 0 as the xwindow_id will tell the overlay to

   158  * stop using that window and create an internal one.

   159  */

   160 #ifdef __SYMBIAN32__

   161 EXPORT_C

   162 #endif

   163 

   164 void

   165 gst_x_overlay_set_xwindow_id (GstXOverlay * overlay, gulong xwindow_id)

   166 {

   167   GstXOverlayClass *klass;

   168 

   169   g_return_if_fail (overlay != NULL);

   170   g_return_if_fail (GST_IS_X_OVERLAY (overlay));

   171 

   172   klass = GST_X_OVERLAY_GET_CLASS (overlay);

   173 

   174   if (klass->set_xwindow_id) {

   175     klass->set_xwindow_id (overlay, xwindow_id);

   176   }

   177 }

   178 

   179 /**

   180  * gst_x_overlay_got_xwindow_id:

   181  * @overlay: a #GstXOverlay which got a XWindow.

   182  * @xwindow_id: a #XID referencing the XWindow.

   183  *

   184  * This will post a "have-xwindow-id" element message on the bus.

   185  *

   186  * This function should only be used by video overlay plugin developers.

   187  */

   188 #ifdef __SYMBIAN32__

   189 EXPORT_C

   190 #endif

   191 

   192 void

   193 gst_x_overlay_got_xwindow_id (GstXOverlay * overlay, gulong xwindow_id)

   194 {

   195   GstStructure *s;

   196   GstMessage *msg;

   197 

   198   g_return_if_fail (overlay != NULL);

   199   g_return_if_fail (GST_IS_X_OVERLAY (overlay));

   200 

   201   GST_LOG_OBJECT (GST_OBJECT (overlay), "xwindow_id = %lu", xwindow_id);

   202   s = gst_structure_new ("have-xwindow-id", "xwindow-id", G_TYPE_ULONG,

   203       xwindow_id, NULL);

   204   msg = gst_message_new_element (GST_OBJECT (overlay), s);

   205   gst_element_post_message (GST_ELEMENT (overlay), msg);

   206 }

   207 

   208 /**

   209  * gst_x_overlay_prepare_xwindow_id:

   210  * @overlay: a #GstXOverlay which does not yet have an XWindow.

   211  *

   212  * This will post a "prepare-xwindow-id" element message on the bus

   213  * to give applications an opportunity to call 

   214  * gst_x_overlay_set_xwindow_id() before a plugin creates its own

   215  * window.

   216  *

   217  * This function should only be used by video overlay plugin developers.

   218  */

   219 #ifdef __SYMBIAN32__

   220 EXPORT_C

   221 #endif

   222 

   223 void

   224 gst_x_overlay_prepare_xwindow_id (GstXOverlay * overlay)

   225 {

   226   GstStructure *s;

   227   GstMessage *msg;

   228 

   229   g_return_if_fail (overlay != NULL);

   230   g_return_if_fail (GST_IS_X_OVERLAY (overlay));

   231 

   232   GST_LOG_OBJECT (GST_OBJECT (overlay), "prepare xwindow_id");

   233   s = gst_structure_new ("prepare-xwindow-id", NULL);

   234   msg = gst_message_new_element (GST_OBJECT (overlay), s);

   235   gst_element_post_message (GST_ELEMENT (overlay), msg);

   236 }

   237 

   238 /**

   239  * gst_x_overlay_expose:

   240  * @overlay: a #GstXOverlay to expose.

   241  *

   242  * Tell an overlay that it has been exposed. This will redraw the current frame

   243  * in the drawable even if the pipeline is PAUSED.

   244  */

   245 #ifdef __SYMBIAN32__

   246 EXPORT_C

   247 #endif

   248 

   249 void

   250 gst_x_overlay_expose (GstXOverlay * overlay)

   251 {

   252   GstXOverlayClass *klass;

   253 

   254   g_return_if_fail (overlay != NULL);

   255   g_return_if_fail (GST_IS_X_OVERLAY (overlay));

   256 

   257   klass = GST_X_OVERLAY_GET_CLASS (overlay);

   258 

   259   if (klass->expose) {

   260     klass->expose (overlay);

   261   }

   262 }

   263 

   264 /**

   265  * gst_x_overlay_handle_events:

   266  * @overlay: a #GstXOverlay to expose.

   267  * @handle_events: a #gboolean indicating if events should be handled or not.

   268  *

   269  * Tell an overlay that it should handle events from the window system. These

   270  * events are forwared upstream as navigation events. In some window system,

   271  * events are not propagated in the window hierarchy if a client is listening

   272  * for them. This method allows you to disable events handling completely

   273  * from the XOverlay.

   274  */

   275 #ifdef __SYMBIAN32__

   276 EXPORT_C

   277 #endif

   278 

   279 void

   280 gst_x_overlay_handle_events (GstXOverlay * overlay, gboolean handle_events)

   281 {

   282   GstXOverlayClass *klass;

   283 

   284   g_return_if_fail (overlay != NULL);

   285   g_return_if_fail (GST_IS_X_OVERLAY (overlay));

   286 

   287   klass = GST_X_OVERLAY_GET_CLASS (overlay);

   288 

   289   if (klass->handle_events) {

   290     klass->handle_events (overlay, handle_events);

   291   }

   292 }